For any such regime to have teeth, budgetary deficit and debt limits would need to be quantified. However, any quantified limits would need to assume specific macroeconomic and GDP growth scenarios, which in practice will almost always differ from initial expectations.

Eurozone states would in practice see themselves as operating in an unduly inflexible financial straitjacket, which could not flex appropriately as macroeconomic circumstances and market pressures change. This would be a recipe for further discord and instability, which is presumably the opposite of what the…